(DO NOT MERGE) Fix pub issue #58043: Copy crash in Android 4.3...

...when clipboard listener attached

We need to clear the calling identity before dispatching change
notifications.  Also make this more robust, so that in the face
of any failure we will clean up the broadcast state.

Integrated from master.

Change-Id: I05e1f76ffd486439535631fe4062dabe94bd2ccf